Grade 12 Agricultural science notes

1. ANIMAL STUDIES
ANIMAL NUTRITION
1. NUTRITION:
 The scientific study of nourishment in animals.
 An animal is feed on food material containing minerals, vitamins, carbohydrates,
proteins and fats.
 Such nutrients promote growth and development, as well as production and
reproduction.
2. ALIMENTARY CANAL (DIGESTIVE TRACT)
 a tube which extends from the mouth to the anus/cloaca/vent
 Path followed by food when it enters the mouth and exits the anus/cloaca/vent as waste
products.
3. DIGESTIVE SYSTEM
 A set of organs in the alimentary canal which are responsible for digestion in animal
body as well as accessory digestive organs.
 Accessory organs. I.e. liver, pancreas, salivary glands.
 Digestion is the breakdown of complex food molecules to simple molecules. i.e.
mechanical digestion and followed by chemical digestion.
4. ALIMENTARY CANAL VISAS DIGESTIVE SYSTEM
• Alimentary canal is unabridged tube extending from the mouth cavity to the anus/cloaca
and in cattle it consists of the following parts. 1) Mouth cavity, 2) pharynx, 3)
oesophagus/gullet, 4) stomach, 5) small intestine, 6) large intestine/colon and 7) anus.
• Digestive system is a number of organs/parts forming the alimentary canal as well as
accessory digestive organs and in cattle it consist of 1) mouth cavity, 2) pharynx, 3)
oesophagus/gullet, 4) stomach, 5) small intestine, 6) large intestine/colon, 7) anus, 8)
salivary glands, 9) pancreas and 10) liver.
5. ALIMENTARY CANAL AND DIGESTIVE SYSTEM OF:
o External structure for each of the.
o Moolman and burger: pages 2, ET 6.
o Kuun et al: pages 4, 8 et 11
NB make a comprehensive illustration of the alimentary canal using other materials such as
the previous question papers and study aids.
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2. 6. COMPARISON OF EXTERNAL STRUCTURES OF THE PIG, CATTLE AND FOWL
 By looking at the illustration of the three, a number of differences are identified, i.e. lips,
beak, teeth, simple stomach, compound stomach, complex stomach, caeca, anus,
cloaca/vent.
 Table 2, pages 21 from Kuun et al, should be used for better understanding.
Parts of the alimentary
canal
Pig Cow Fowl
Mouth
Oesophagus
Stomach
Small intestines
Colon
7. INTERNAL STRUCTURES OF THE COMPOUND STOMACH (CATTLE)
 Rumen
 Consist of densely packed papillae/finger like protrusion.
 Large stomach
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3.  Reticulum
 Honeycomb/net stomach
 ‘hardware stomach’ all foreign objects like nails, glass, wire and plastic.- collect in the
reticulum. Some of this object can pierce through the walls of the stomach and damage
the heart and the lungs.
 Omasum (morothwane)
 Leaf stomach
 Leaf-shaped protrusions or folds of leaves.
 Abomasum
 Comparable to a simple stomach
 Milk/true stomach
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4. 8. INTERNAL STRUCTURE OF THE SMALL INTESTINE (CATTLE)
 Glands of Lieberkuhn in the villus secrete digestive enzymes.
 Glands of Brunner (duodenum) play a protective role against the effects of acid of gastric
juices.
 Villi are microscopic finger-like growth which are found in fold in small intestine of the
epithelium tissue.
 Each villus contains capillary blood vessels and central lymph.
 Dorsal aorta supplies blood to the villi
 Portal vein system transport the blood, rich in ruminants, to be liver.
NB. Three kinds of glands of the small intestine
 Intestinal glands/crypts of Lieberkuhn
 Duodenal glands/Brunner’s glands
 Lymphoid tissue/Peyer’s patch
LONGITUDINAL SECTION OF A VILLUS
DIGESTION
it is breakdown of complex food (insoluble) molecules to simple (soluble) molecules; the process
starts with mechanical/physical and followed by chemical/enzymatic action.
PURPOSE OF DIGESTION
 For absorption to take place. Absorption of:-
 Carbohydrates
 Proteins
 Lipids
 Minerals
 Vitamins
9. RUMINANTS
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5. Animals that chew cud with complex stomach including the rumen. E.g. cattle, sheep, goat,
horse etc.
10. NON-RUMINANTS
Animals that do not chew cud with simple stomach. E.g. pig
11. DIGESTION IN NON RUMINANT (PIG)
INTAKE OF FOOD
 Lips, teeth and tongue are used for intake of food.
DIGESTON IN THE MOUTH
⇒ Molars and premolars are used to chew and grind food.
FUNCTION OF THE TONGUE
℘ Taste organ
℘ Helps chewing process
℘ Helps swallowing process
℘ Assists in mixing of food
℘ Food intake
℘ Helps in demising presence of foreign objects
FUNCTION OF THE SALIVA
 Moistens and lubricates the food
 Digestion-salivary amylase(ptyalin) – changes poly to monosaccharide
 Alkaline-suitable for enzyme reaction – neutralizes acids in the mouth cavity.
 Solvent for food
 Binding effect – formation of bolus
 Moistens and protects the mouth.
NB no ptyalin in ruminants. E.g. cattle
SWALLOWING
Food in the form bolus in the mouth cavity is taken into the stomach through the gullet.
PERISTALSIS
DEF: - a process by which food bolus is transported from the mouth cavity into the stomach.
RETRO PERISTALSIS
DEF: - the opposite of peristalsis (vomiting)
DIGESTION IN THE STOMACH
FUNCTION OF THE STOMACH
 Storage organ
 Mixing of chime
 Secretion of HCL, pepsinogen and rennin
 Partial digestion of protein to peptones
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6.  CHO are changed to glucose
FUNCTION OF THE HCL
 Antiseptic
 Activates pepsinogen to pepsin
 Neutralizes alkaline medium of saliva
 Creates pH required by pepsin and rennin
 Changes disaccharides (sucrose) to monosaccharide (glucose & fructose)
DIGESTION IN THE SMALL INTESTINES
Digestion is controlled by:-
 Bile
 Pancreatic juice
 Duodenal juice
FUNCTION OF THE LIVER
♪ Secretes bile
♪ Stores glycogen
♪ Detoxifies toxins in the blood stream
♪ Sores vitamin (A, K, D & E)
♪ Stores copper
♪ Helps in formation of blood
♪ Prevents blood clotting-heparin
♪ Synthesis certain proteins
FUNCTION OF THE BILE
 Neutralizes the enzymes
 Creates alkaline medium for enzymes
 Emulsifies fats
 Enhances peristalsis
 Improves solubility of fat digestion and improves absorption
 Purifies small intestines
 Absorbs fat soluble vitamins
 Antiseptic
FUNCTION OF THE PANCREATIC JUICE
 Neutralizes acid chime from the stomach
 Trypsin changes proteins to amino acids
 Lipase changes fat to fatty acids + glycerol
 Amylase changes starch to glucose
FUNCTION OF THE SACCUS ENTERICUS
 Enterokinases changes trypsinogen to Trypsin
 Repsin changes proteins to amino acids
 Maltase changes maltose to glucose
 Sucrase changes sucrose to glucose + galactose
 Lactase changes lactose to glucose + fructose
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7.  Lipase changes fats to fatty acids + glycerol
DIGESTION IN THE RUMEN
Occurs due to micro-organism, viz
 Bacteria
 Protozoa
REQUIREMENTS OF MICRO-ORGANISM/FLORA (MICROBES) FOR FERMENTATION.
 Nitrogen to synthesis microbial proteins
 Regular supply of digestible CHO’s for energy
 Sufficient mineral nutrients (nitrogen, phosphorus & cobalt) for growth and
reproduction
 Anaerobic environment
 Maintenance of constant body temp.
 Continuous movement of food and removal of end and waste products.
 Favorable pH of 6,5
FUNCTION OF MICRO-FLORA
 Hydrolyses of proteins to amino acid, peptides and ammonia + n-compounds.
 Synthesis of amino acid from NPN +energy (such as urea)
 Digestion of cellulose to volatile fatty acids
 Synthesis of vitamin K + B complex only if enough cobalt is present.
ABSORPTION PROCESS
DEF: - process whereby the end products of digestion enter the blood stream and lymphatic system for
distribution to the whole body.
Process occurs by:-
 Diffusion
 Active diffusion
DIGESTION IN THE COLON
 Creation of mucus for lubrication
 Absorption of water
 Absorption of mineral salts by the blood
 Fermentation of waste products
 Vitamin B complex are synthesized and absorption
DIGESTION IN THE RUMINATS
INTAKE OF FOOD
 Uses the lips, cushion and tongue to take in food.
 No ptyalin in saliva
ROUTE OF FOOD AND CHEWING THE CUD
 Grazing period: food is rapidly ingested and stored in both rumen and reticulum
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8.  Resting period: food is taken from rumen + reticulum into the mouth cavity for chewing to
take place.
 Peristalsis : occurs during grazing period
 Retro peristalsis: occurs during resting period.
 Chewing cud: occurs when food from the stomach is taken into the mouth cavity and
mechanically digested/chewed by molars and premolars
NB young suckling ruminants use the abomasums and the other three compartments are under
developed.
FORMS IN WHICH NUTRIENTS ARE ABSORBED
Nutrients Form of absorption
1. Proteins Amino acids
2. Carbohydrates Glucose
3. Cellulose Fatty acids, salts of organic acids
4. Fats Fatty acids, glycerol
5. Minerals Any soluble form
6. Vitamins Any soluble form
AREAS OF ABSORPTION
Ruminants Non ruminant Fowl
Stomach Stomach Crop
Small intestine Small intestine Small intestine
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9. COMPONENT OF FEED
STOCK FEED BASICALLY CONSISTS OF: -
 Moist matter
 Dry matter
TYPES OF FEED
Feed
Concentrates roughages
Carbohydrates-rich protein-rich dry-roughages succulent
e.g. oats e.g. lupin seed roughage
e.g. green
lucerne, silage
legume protein rich non legume carbohydrate rich
e.g. lucerne hay e.g. grass
CONCEPT:
Concentrates:
 Feeds which per unit mass, have a small volume but high percentage of digestible nutrients.
 Contain more than 60 TDN, and less than 20% crude fibre.
FUNCTIONS OF WATER
1. Transport
 Acts as a solvent and transport medium during the absorption of food and minerals.
 Cleanses the alimentary canal.
 Transport medium for the secretions of exocrine glands, blood nutrients and metabolic wastes.
2. Temperature regulation
 Controls body temperature through sweat during hot days.
3. Chemical reactions
 Medium of all chemical reactions.
 Takes part in hydrolytic reactions.
4. Protection
 Cushion to absorb shocks of vital organs ie. Brain & spinal cord.
 Serves as an internal & external lubricant. (lungs, joints, heart, eyes)
 Protects the embryo against shocks, temp changes and desiccation.
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10. 5. Body support
 Give shape to the body by means of tension in the cells (turgor pressure)
SOURCES OF WATER
 Drinking water
 Present in food
 Metabolic water
FUNCTIONS OF PROTEINS
1. Growth and repair
 Repair worn-out tissues building of new tissues
2. Regulation of body activities
 Hormones & enzymes controls metabolic activities
3. Structural components of cells
 Part of cell membranes
4. Required for production
 Milk, wool, meat & eggs
5. Reserve energy source
 Excess proteins can serve as a reserve source energy
6. Reproduction
 Required for formation of hormones & structure related to reproduction.
7. Body Support, Movement and Protection
 Muscle tissue (actin & myosin)
 Tendons & ligaments (collagen & elastin)
 Hair, nails, horns (keratin)
FUNCTIONS OF CARBOHYDRATES
1. Energy
o Source of energy for metabolic processes
2. Heat generation
o During digestion, heat is produced which maintains the body heat.
3. Energy storage
o Stored as glycogen
o Excess carbohydrates may be converted into animal fat.
o Important for fattening farm animals.
4. Production
o Used for manufacturing of lactose & butterfat
5. Nutrition
o Provides bulkiness
o Needed for normal functioning of the alimentary canal
6. Structural components
o Combination of proteins or lipids serves as structural components of cells.
7. Heredity and cell functioning
o Ribose & deoxyribose are components of RNA & DNA
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11. FUNCTIONS OF LIPIDS (FATS & OILS)
1. Energy
♪ Supply more energy than carbohydrates & proteins.
2. Energy storage
♪ Excess fats are converted into animal fat
3. Protection
♪ Layers of fat protect the body against shock & injuries.
4. Nutrition
♪ Assist in absorption of vit A, D, E & K
♪ Assist in absorption of calcium from the ration.
5. Temperature control
♪ Effective insulator against heat losses and gains.
6. Structural components
♪ Phospholipids are important part of cell membrane.
7. Waterproofing
♪ Form hydrophobic layers on wool and feathers.
FUNCTION OF CONCENTRATES
 Essential for optimum growth
 Supply the necessary proteins, CHO and fats
 Used to balance rations
 Used for increased production of milk, eggs etc.
 Increase the digestibility of ration
 Source of fair quantity of minerals
 Indispensable in fowls and pig’s ration
PROTEIN RICH CONCENTRATES
E.G. fish-meal, meat-meal, blood-meal, crawfish-meal, lupins, peanuts, soya-beans, cotton-seed,
linseed and sunflower.
CARBOHYDRATES RICH CONCENTRATES
E.G. maize, oats, barley, rye, and sorghum.
FISH-MEAL AS PROTEIN-RICH CONCENTRATE
COMPOSITION
 60% crude protein
 48,5% digestible protein
 10% maximum fats
 4% salt
 +/- 20% mineral
 72% TDN
 Rich Ca and P
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12.  NR 23,5
/48,5 = 1:0,48
CHARACTERISTICS
 Expensive
 High BV
 Source of vit A, D and B12
 Protein supplement
 Not palatable to ruminants
SUITABILITY
 Growth : suitable
 Fattening : suitable
 Production : suitable
 Energy : suitable
MINERALS
Mineral Form
Calcium and phosphorus Mono- and dicalcium phosphate
Bone meal
Calcium bicarbonate
Sodium chloride Sodium chloride
Magnesium Magnesium sulphate
Sulphur Inorganic Sulphur
Iron Iron capsule
Iron sulphate
Copper Copper sulphate
Cobalt Cobalt sulphate
Cobalt chloride
Zinc Zinc sulphate
Zinc carbonate
Zinc oxide
Iodine Potassium iodide
Sodium iodide
Iodized chloride
METHODS OF SUPPLEMENTING MINERALS
 Licks e.g. stock salt
 Drinking troughs e.g. soluble supplement like sodium phosphate are dissolved in water
in drinking through.
 Supplementing rations: when compounding ration, different minerals are included.
 Dosing e.g. piece of cobalt given to ruminant and release in the rumen.
 Cafeteria style / free choice / ad lib: minerals are exposed and take them as they want.
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13.  Injection: injecting deficient minerals e.g. calcium.
 Soil sods : iron supplemented by red soil
VITAMINS
E.G. A, D, E, K, B1, B2, B6, B12
GENERAL FUNCTIONS OF VITAMINS
 Structural parts of enzymes and co-enzymes.
 Activates enzyme systems.
 Regulates the metabolism of the end products of digestion.
 Play a role in the transfer of energy in the body.
VITAMIN A
 Found in the body fat of cattle, feathers of birds, egg yolk and butterfat.

FUNCTIONS
o Growth and maintenance of cell structure.
o Enables retina to form an image in the dark.
o Normal bone formation.
o Normal reproduction.
o Development of the unborn foetus and in the hatching of eggs.
DEFICIENCY SYMPTOMS
• Night blindness.
• Anorexia
• Decrease of normal growth in an animal.
• Lower fertility.
• Reduced resistance to bacterial infection.
• Abnormal development of the skeleton.
• Deformation and ulceration of the cornea.
VITAMIN B COMPLEX

FUNCTIONS
o
DEFICIENCY SYMPTOMS
•
VITAMIN B2 (RIBOFLAVIN)

FUNCTIONS
o
DEFICIENCY SYMPTOMS
•
VITAMIN B12

FUNCTIONS
o
DEFICIENCY SYMPTOMS
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14. •
VITAMIN D

FUNCTIONS
o
DEFICIENCY SYMPTOMS
•
VITAMIN E

FUNCTIONS
o
DEFICIENCY SYMPTOMS
•
VITAMIN K

FUNCTIONS
o
DEFICIENCY SYMPTOMS
•
METHODS OF SUPPLEMENTING VIT
 Injection
 Mixed with rations
NON-PROTEIN NITROGEN
 Urea : is toxic
 Biuret : less soluble as compared to urea
METHODS OF SUPPLEMENTING NPN
 Concentrate mixture
 Licks
 Addition of molasses
SYNTHETHIC AMINO ACIDS
 Methionine
 Lysine
METHODS OF SUPPLEMENTING SYNTHETIC AMINO ACID
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15.  Supplementing rations
GROWTH STIMULANTS
 no nutritive value
 stimulate appetite
 improve digestion
 alter metabolism
 control diseases or parasites
DIFFERENT TYPES OF GROWTH STIMULANTS
 antibiotics (antimicrobials)
 hormones
 pH regulators/buffers
 thyroid regulators
 surfactants
 tranquilizers
 feed flavours
 anthelmintics
ADVANTAGES & DISADVANTAGES OF USING GROWTH STIMULANTS
ADVANTAGES DISADVANTAGES
♪ Influence the metabolic rate and subsequently
also fattening of the animal.
♪ Animals grow faster so they will be ready for
marketing faster.
♪ Larger carcass weight and easy to administer.
♪ More economical weight gain – more effective
conversion ratio in the animal.
 Growing resistance to buying animal
products treated with growth stimulants.
 Marketing of animal treated with
stimulants is more difficult.
 Growing evidence that growth stimulants
may have a negative influence on the
health of people.
 Treated animals cannot be marketed
immediately. (residual effect)
METHODS OF DETERMINING THE COEFFICIENT OF DIGESTIBILTY.
Def: - percentage of the nutrients that are digested, that is absorbed by the animal.
FACTORS THAT DETERMINE DIGESTIBILITY
 Animal factor
 Food composition
 Ration composition
 Preparation of feed
 Level of feeding/quantity of feed ingested
 Age of plants
 Nutritive ratio
 Individuality
PROCESSES TO IMPROVE DIGESTIBILITY
 Grinding
15

16.  Pelleting
 Boiling
 Roasting
 Cracking (crushing & rolling)
 Cutting of plants for making hay
 Method of making hay
 Soaking the grain
 Cooking of grains and cereals
PLANNING OF THE FEEDING PROGRAMME
DEF: - prescription of feeds to specific animals and order in which such feeds are given/taken by
animals at certain intervals.
 in preparation (planning) of feeding programme, the following concepts are to be
considered, viz.,
1. DIGESTIBLE ENERGY
 gross energy minus energy lost through the faeces
 i.e. the actual amount of energy used by the body
2. DRY MATTER
 constituent of a feed except the water content
 expressed as a percentage
3. NUTRITIVE RATIO
 the proportion of digestible proteins, CHO and fats
 calculation of NR
CALCULATION
GIVEN TDN = 80%, DP = 10%
D CHO + FATS = TDN – DP
= 80% - 10%
= 70%
NR = 1: DCHO + FATS
DP
= 1: 70%
10%
= 1: 7
NB: narrow NR is less than 1:6
Wide NR is greater than 1:6
4. MAINTENCE RATION
 ration given exclusively for sustaining an animal’s state of well being health from day to
day.
 given to non-producing, not growing animals.
5. PRODUCTION RATION
 the part of ration which is supplied over and above the maintenance ration to enable
animals to produce energy or products such as milk, wool etc.
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17. NUTRITIVE REQUIREMENTS FOR MAINTENACE GROWTH, REPRODUCTION &
PRODUCTION
INCREASE OF PRODUCTION THROUGH SHELTER
 for maximum production, constant body temperature is needed
 constant body temperature is obtained by balancing the body heat gain and heat loss
METHODS OF PROVIDING SHELTER FOR ANIMALS
 trees i.e. next to drinking places/troughs
 climate i.e. cover & protection units
 controlled environment i.e. micro climate for animals
 kennel i.e. both climate and controlled environment together
PROTECTION OF ANIMALS AGAINST TEMPERATURE FLACTUATUION
1. hot weather
 more energy used/wasted
2. cold weather
 more energy needed/required
3. wind
 temperature drop
4. rain
 lowers the temperature
HANDLING AND BEHAVIOUR OF FARM ANIMALS
 Animals are reluctant to move towards dark areas:- all areas must have sufficient light
 They can distinguish colour:- use same colour in your buildings and handling facilities
 They hear sounds of higher frequencies:- avoid loud noises
 Have well developed sense of smell:- if they smell blood or strange animals they will over-react
 They protect their personal space:- keep a critical distance at all times
 Social order & pecking order:- handlers must respect this order
 Follow instinct:- never try to separate animals unnecessary
 Herding instinct:- even if you need to handle one animal never try to separate animals unnecessary
 Temperamental animals or herd should be treated carefully
GRAZING BEHAVIOUR
 Bulk grazers (cattle, zebra or buffalo) will graze tall grass species. And usually have broad mouth.
 Concentrates grazers (sheep, springbok) will graze shorter and tender grass. And they have small
mouths.
 Browsers (goats, giraffes) will graze but mostly they prefer trees. And they have mouth smaller to
nibble between the thorns.
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Compiled by Msiza J.M